Monday, February 11, 2013

Diet Diabetes

By Mark Hamer

Did you know that consuming too
much sugar increases the likelihood that you’ll develop Type II Diabetes? Of
course you did. But how many of you, or your parents, drink diet soda to avoid
this risk? What if I were to tell you that drinking diet soda might be
increasing these risks? I’m asking a lot of questions here, but I doubt I’m the
only one of us to have thought about this. Some of these questions have obvious
answers while others are slightly more convoluted. I have always had a great interest
in the insulin-dependent response to glucose and so upon reading an article a
couple weeks ago linking diet sodas to diabetes I immediately became intrigued.
I began to explore the topic and the more I learned the more it made sense.
Here’s what I found.

Disclaimer: In most cases from
this point on I will simply

use “diabetes” when referring to Type II Diabetes

Before we develop too heavily on the
topic of diet soda and diabetes, I think that it is first important to outline
the body’s natural response to sugar and what exactly goes awry in people that
develop diabetes. In a healthy adult the uptake of glucose following a meal is regulated
by the release of insulin from the pancreas. This acts as a signal for other
cells throughout the body to begin the transport of glucose across their
membranes, effectively lowering the concentration of glucose in the blood. A
type 2 diabetic, however, handles things entirely differently. When a person
chronically overloads their glucose response system they begin to wear out some
of the critical pieces of the cellular machinery involved in that response. For
those that develop diabetes there are two mechanisms that usually fail; the
ability for the pancreas to release insulin (insulin secretion) and the ability
for cells to correctly interpret the signal that insulin is supposed to send
(insulin resistance). This in turn increases the blood concentration of
glucose, a telltale sign of diabetes.

A very basic overview of insulin resistance

But we’re talking about diet, “sugar free”, soda aren’t we? Let's get back to the original question: Does it make sense that sodas containing artificial sweeteners really could contribute to the onset of diabetes? The simple answer is yes, and if you think about it it makes perfect sense. Artificial sweeteners were originally developed in an attempt to limit caloric intake yet retain the illusion of sweetness that humans inherently crave. The whole idea is to trick your taste buds in to thinking you’re consuming sugar but from there it remains chemically inert. What we are only recently beginning to understand is that artificial sweeteners such as aspartame, acesulfame potassium, and saccharine might continue to trick the human body further than intended.

Aspartame: The most common artificial sweetener in use today

Up until recently most of the scientific community seemed to
be in denial of the fact that artificial sweeteners could be just as bad, if
not worse than good old-fashioned sugar. Many of the studies performed to test
the effect of sweeteners such as aspartame used small doses and were not
extensive enough to extrapolate long-term results from. However, a more recent
fourteen year study in France that monitored beverage consumption (among many
other things) in over 60,000 women provides conclusions that are hard to argue
against. It has shown that drinking “light” or “diet” soft drinks containing these synthetic sweeteners is correlated
with the likelihood of developing diabetes in a dose-dependent manner. This
data firmly supports the notion that continued consumption of artificial
sweeteners is taking catastrophic toll on the normal physiological glucose
response of those who use them. Here’s how:

On a broad scale it is thought that the consumption of
calorie-less food items such as soda may, aside any direct physiological
effects, induce changes in the psyche of those who drink them. So much so, they
might “increase hedonistic desires for sweetness and more energy-dense foods.” In other words, your brain thinks it is getting sugar all the time so it
continues to crave it, even if it’s not “diet”.

If we take a closer look at the physiological effects these
sweeteners are having on those who consume them, we might come to a clearer
understanding of the damage they are really incurring on the natural
insulin-dependent response to glucose. In researching the topic I came across
two very interesting articles that support, on a cellular basis, the conclusions
reached by the French E3N study. The first shows that the taste receptor on
your tongue that is responsible for tasting things like sucrose, fructose, and
– you guessed it – artificial sweeteners isn’t isolated to your taste buds. In
fact it is also found in the pancreas where it, when bound by its ligand,
promotes the secretion of insulin. So despite the fact that you’re not getting
calories, you’re releasing insulin. Once this insulin is released it continues to function as it should; i.e. opening glucose transporters on the membrane surfaces of muscle and liver tissue. However, because there is no glucose around to be transported, the cell does not obtain any glucose. It's pretty easy at this point to see how the onset of insulin desensitization could result. The second paper showed similar, dose-dependent, results using acesulfame potassium. At this point the picture should be getting pretty clear. These artificial sweeteners, though never broken down, are eliciting the same physiological response as glucose normally does. And if a person is consuming these and real sugar, as is often the case, overloading the system really isn't that difficult to do.

Before I make my final remarks I would like to add that
clearly it isn’t just diet soda that’s responsible for the current diabetes
epidemic. There are many other aspects of modern life that are contributing to the prevalence of this disease. Everything from the food we eat to the sedentary lifestyle we sustain is having a large effect on our ability to respond to glucose properly. Even the hyper-sterile environments we live in have been linked to increased risk of diabetes
(those of you interested should check out WU et al. very cool stuff)

That said, we as consumers have clearly been misinformed. I
feel that until looking deeply in to the topic I was unaware, albeit the
occasional “it’ll give you cancer,” of the dangers of diet soda. But after
thinking about it for a while it really does make a lot of sense. There’s no
free lunch.